In this type of plant-culturing tool, a planting container for accommodating a plant floats on the water for cultivating a plant inside the water storage container. In this kind of plant-culturing tool, the amount that the planting container sinks in the water for cultivation automatically increases and a quantity of water commensurate to the growth of the plant is supplied when the plant becomes heavy in conjunction with plant growth. Therefore, demand has grown in recent years for a plant-culturing tool that is convenient to use.
However, the orientation of the planting container becomes unstable when the plant grows and the center of gravity shifts upward because the planting container that accommodates the plant floats in water. For this reason, a plant-culturing tool is known that is provided with a guide mechanism for guiding the vertical floating movement of the planting container in relation to the water storage container, and the tool is configured so that the orientation of the planting container is maintained.    [Patent Document 1] Japanese Laid-open Patent Application No. 2004-242501